Laminating resins having low organic emission (III)

ABSTRACT

A laminating resin is made from (1) an unsaturated polyester resin, (2) a diacrylate or dimethacrylate of alkoxylated bisphenol-A, and (3) styrene, divinyl benzene or a combination thereof. The resin achieves excellent laminating resin properties, and is significantly inhibited from emitting volatiles during use.

RELATED APPLICATIONS

This is a divisional of application Ser. No. 225,107, filed Apr. 8,1994, now U.S. Pat. No. 5,492,668, which is a continuation-in-part ofour application Ser. No. 024,022, filed Mar. 1, 1993, now abandoned.

TECHNICAL FIELD

This invention relates to resin compositions which cure as they areshaped, laminated, brushed, sprayed or otherwise more or lessincrementally placed into the space where they are to form a product;such resins are broadly known as laminating resins, commonly have anunsaturated polyester resin base, are mixed with glass fiberreinforcement, and nearly always are employed in a solution of anorganic monomer such as styrene. The organic monomer is intended tocopolymerize with the resin but typically and notoriously tends also tovolatilize in significant amounts into the workplace environment. Thepresent invention is a composition and method which can be used inexisting equipment, procedures, and workplaces, but which will emit farless monomer than the typical laminating resin and method heretofore.

BACKGROUND OF THE INVENTION

Many attempts have been made to devise laminating resins having lowvolatile emissions and still meet the physical specifications and otherdesirable properties of the end products, while remaining relativelyeasy to use. In Lee U.S. Pat. No. 4,465,806, for example, a more or lessconventional unsaturated polyester resin is combined with, instead ofthe usual styrene, a reaction product of a polyepoxy compound andacrylic or methacrylic acid which may be the diacrylate of apolyglycidyl ether of bisphenol-A. These compounds are made from epoxycompounds, and the author of U.S. Pat. No. 4,465,806 requires that asignificant portion of the epoxy groups be unreacted for use in theirresin. Moreover, unlike the present invention, they form pendant OHgroups.

Ethoxylated, difunctional, bisphenol-A has been used in the past as aningredient in various types of resins, generally resins which include asignificant diisocyanate component, as in Ford, Jr. et al U.S. Pat. No.3,876,726.

European Patent Application 0 234 692 discloses a composition said to beuseful as a molding resin, having the virtue of a low residual monomerconcentration in the final product. The gist of the disclosure appearsto be that dimethacrylates such as ethoxylated bisphenol-Adimethacrylate can be used as components of otherwise more or lessconventional unsaturated polyester resins to reduce the amount ofresidual styrene monomer in contained molding processes such as cellmolding, compression molding, and sheet molding. See also Reid and RexU.S. Pat. No. 5,202,366, which includes a low-profile additive in asimilar composition.

The daunting problem of volatile emissions during spray-up or otherlaminating procedures has until now been unsolved. Applicants' dramaticresults detailed herein show that lamination can be performed withsignificantly reduced emissions in the workplace.

SUMMARY OF THE INVENTION

Our new laminating method employs a resin comprising three components.The first is a more or less conventional base resin comprising glycolsand unsaturated dicarboxylic acids; optionally the base resin may alsocontain a saturated dicarboxylic acid. In polymeric form, they aretypically maleic and phthalic acid residues, with optional isophthalicresidues, interspersed with glycol residues. These glycols are commonlyethylene glycol, diethylene glycol, propylene glycol and dipropyleneglycol, usually as mixtures, but many other glycols can be utilized;dicyclopentadiene may be included as well, as is known in the art. Thesecond component is a diacrylate or dimethacrylate of alkoxylatedbisphenol-A of the formula ##STR1## where m and n are independentlynumbers from 1 to about 10, R¹ and R² are independently, in each alkoxygroup, hydrogen or CH₃ and each R³ is also independently hydrogen orCH₃. These two ingredients may be present in weight ratios of about2.0:1 to about 0.5:1. The composition also includes about 10% to 60%,based on the total of the two above ingredients, of styrene, divinylbenzene or mixtures thereof. The above-described composition may alsoinclude from 1% to about 10% of N-vinyl pyrrolidone or 1% to about 20%cyclohexyl methacrylate or both, and/or 1% to about 30% ethylene glycoldimethacrylate, or vinyl toluene, all based on overall composition. Thecomposition will also tolerate many other minor ingredients known to beuseful in the unsaturated polyester and laminating art.

The compounds of interest, styrene and divinyl benzene, may be describedas benzene ring compounds of the formula C₆ H.sub.(6-x) (CH═CH₂)_(x)where x is 1 or 2.

DETAILED DESCRIPTION OF THE INVENTION

While the problem at hand is to create a formulation which drasticallydiffers from commercial standard laminating resins in terms of volatileemissions during application, the market dictates that it must beaccomplished without significantly altering the widely used equipmentand techniques of application. Accordingly, the following criteria areto be kept in mind at all times:

1. Reduced emission of volatile organic compounds--regulations willbecome more stringent with time.

2. Less potential hazard to human health and theenvironment--regulations will also become more stringent with time.

3. Minimal increase in cost when commercialized, and reason to believecost will be reduced in the long run.

4. Compatibility between components of the resin system.

5. Reactivity that is similar to that of other commercial polyesterresins.

6. Viscosity that is similar to that of other commercial polyesterresins--100 to 400 cps.

7. Ability to wet glass and bond to other components of an assembly.

Many criteria have to be balanced, and, with thousands of chemicals toconsider, analysis of the combinations and their effects is extremelydifficult. One must decide on the important functions and properties,settle on a systematic but simple screening process, and try to developa short list of prospective formulations which have a good chance ofmeeting all the criteria within a practical time period.

The proliferation of input variables to attain these objectives may befurther appreciated by considering the more or less conventionalunsaturated polyester compositions which may be used as a base. They areprepared by polycondensation of polycarboxylic acid derivatives, one ofwhich must be an alpha, beta-ethylenically unsaturated polycarboxylicacid, and polyols. By polycarboxylic acid derivatives we mean to includepolycarboxylic acids, their esters of lower alcohols, their acidchlorides and their anhydrides.

The ratio of polycarboxylic acid to polyol is usually a 1:1 molar ratio.However, in most esterification processes, a slight excess of polyol isutilized to compensate for polyol losses during esterification. Also,although dicarboxylic acids and diols are most frequently utilized andthe 1:1 molar ratio is prevalent, the utilization of triols and the likerequires the ratio of acid to polyol to be stated more precisely as oneequivalent of acid per equivalent of polyol.

The unsaturated polyesters useful in this invention may be prepared froman acid mixture wherein the unsaturated polycarboxylic acid comprises aslittle as 20 mole percent of the total acids present, although it isgenerally preferred that the unsaturated polycarboxylic acid comprisesabout 30% or more of the total acid content.

Some of the unsaturated polycarboxylic acids useful in preparingunsaturated polyesters used in this invention include:

    ______________________________________                                        Maleic acid        Citraconic acid                                            Fumaric acid       Glutaconic acid                                            Itaconic acid      Chloromaleic acid                                          Mesaconic acid                                                                ______________________________________                                    

and the like, wherein the term "acid" is used to include thecorresponding anhydrides where such anhydrides exist.

Some of the saturated and aromatically unsaturated polycarboxylic acidsoptionally useful in preparing unsaturated polyesters used in thisinvention include:

    ______________________________________                                        Phthalic acid        Isophthalic acid                                         Tetrahydrophthalic acid                                                                            Hexahydrophthalic acid                                   Endomethylene tetrahydrophthalic acid                                                              Glutaric acid                                            Tetrachlorophthalic acid                                                                           Suberic acid                                             Hexachloroendomethylene                                                                            Sebacic acid                                             tetrahydrophthalic acid                                                       Succinic acid                                                                 Adipic acid                                                                   ______________________________________                                    

and the like, wherein the term "acid" includes the correspondinganhydrides where such anhydrides exist.

Polyols useful in preparing polyesters for use in this invention arepolyfunctional alcohols of the type conventionally utilized in polyesterpreparation. Such polyols include:

    ______________________________________                                        Ethylene glycol        1,5 propanediol                                        Propylene glycol       Triethylene glycol                                     Butylene glycol        Glycerol                                               Diethylene glycol      1,4,6-hexanetriol                                      Trimethylolpropane     Trimethylolethane                                      Dipropylene glycol     Pentaerythritol                                        Neopentyl glycol                                                              Alkoxylated 2,2-bis(4-hydroxyphenyl)                                          propane                                                                       ______________________________________                                    

and the like. Although diols are generally preferred in the preparationof unsaturated polyesters, the more functional polyols, i.e. polyolshaving a functionality of three to five, are sometimes used.

In addition, dicyclopentadiene may be included and may be considered anormal part of the "base resin" as used herein.

During the development of the formulation, various monomers and monomersubstitutes were screened, using a resin composition (hereafterdesignated "Resin A") prepared from the following ingredients:

    ______________________________________                                        Base Resin*           60 parts by weight                                      12% Cobalt (Promoter) 00.30                                                   Potassium (Co-promoter)                                                                             00.20                                                   N,N-Dimethylacetoacetamide                                                                          00.30                                                   (Accelerator)                                                                 DDM-9 (Initiator)     01.50                                                   Monomer (as indicated below)                                                                        40                                                                    Parts by                                                        *Base Resin (Polymer)                                                                       weight    lbs/100 lbs                                                                              lbs/60 lbs                                 ______________________________________                                        Propylene Glycol                                                                            22.788    31.97      19.18                                      Diethylene Glycol                                                                           04.937    6.93       4.16                                       Phthalic Anhydride                                                                          32.734    45.92      27.55                                      Maleic Anhydride                                                                            10.820    15.18      9.11                                                     71.279    100.00     60.00                                      ______________________________________                                    

The following "monomers" were utilized with Resin A:

    ______________________________________                                                                   Exo-                                                                          therm Gel Time                                                                             Interval                              Monomer  Mod L.sup.1)                                                                           Viscosity                                                                              °F.                                                                          min:sec                                                                              min:sec                               ______________________________________                                        Styrene  0.120    low      335   4:30   4:39                                  Vinyl    0.120    low      317   4:50   5:04                                  Toluene                                                                       Diallyl  0.000    high     119   19:27  27:43                                 phthalate                                                                     Meth-                                                                         acrylates                                                                     n-butyl  0.001    low      186   40:58  5:28                                  n-hexyl  0.001    incompa-                                                                      tible                                                       isodecyl 0.001    incompa-                                                                      tible                                                       cyclohexyl                                                                             0.001    high*    287   16:50  3:50                                  2-phenoxy-                                                                             0.001    high     196   8:45   3:29                                  ethyl                                                                         allyl    0.001    low      331   18:20  3:37                                  2-hydroxy-                                                                             0.001    low      247   4:48   3:35                                  ethyl                                                                         2-hydroxy-                                                                             0.010    low      249   4:30   3:20                                  ethyl                                                                         dicyclopentyl                                                                          0.001    very high                                                                              199   3:40   4:11                                  isobornyl                                                                              0.000    incompa-                                                                      tible                                                       isophoronyl                                                                            0.010    incompa-                                                                      tible                                                       Dimeth-                                                                       acrylates                                                                     1,6-     0.001    high     241   7:54   3:34                                  hexanediol                                                                    ethylene 0.001    low      275   2:48   3:37                                  glycol (EG)                                                                   ethylene 0.005    low      274   2:52   3:50                                  glycol                                                                        diethylene                                                                             0.001    medium   >210  4:03   2:12                                  glycol                                                                        diethylene                                                                             0.010    medium   252   5:40   3:13                                  glycol                                                                        triethylene                                                                            0.001    medium   241   3:18   3:17                                  glycol                                                                        tetraethylene                                                                          0.001    medium   229   2:52   3:46                                  glycol                                                                        neopentyl                                                                              0.001    high     235   4:20   4:09                                  glycol                                                                        ethoxylated                                                                            0.001    very high                                                                              171   8:50   7:30                                  BPA                                                                           C14 diol 0.001    incompa-                                                                      tible                                                       Tri-                                                                          methacrylate                                                                  trimethylol                                                                            0.001    high     228   2:28   4:25                                  propane                                                                       Mixtures                                                                      30 EG di-                                                                              0.010    medium   295   1:49   3:12                                  methacrylate/                                                                 10 N-vinyl                                                                    pyrrolidinone                                                                 30 EG di-                                                                              0.010    medium   286   3:11   3:29                                  methacrylate/                                                                 10 divinyl                                                                    benzene                                                                       30 vinyl 0.200    low      289   16:10  4:44                                  toluene/                                                                      10 N-vinyl                                                                    pyrrolidinone                                                                 ______________________________________                                         *This was considered unsatisfactory, but when ethoxylated BPA                 dimethacrylate was included to make a 3part mixture, viscosity was            lowered. Of all the above monomers screened, only the Nvinyl                  pyrrolidinone, divinyl benzene, ethylene glycol dimethacrylate, styrene,      cyclohexyl methacrylate, and vinyl toluene were not ruled out. The rest       were eliminated from consideration because they were slow to react with       polyester as shown by long gel time and/or low exotherm or they were not      sufficiently compatible with polyester as shown by high viscosity or the      outright failure to dissolve.                                                 .sup.1) Mod L is 25% hydroquinone in propylene glycol.                   

Liquid resin properties measured in the experiments reported below weregel time, (reported in the tables herein in minutes and seconds, as13:17, for example), room temperature interval time, which is the timebetween gelation and the exothermic peak, room temperature exothermicpeak which is the highest temperature reached in a 100 g mass of resinduring the curing process, Brookfield viscosity, and Barcol hardness byASTM D2583. For volatile emissions, we followed the Rule 1162 StandardMethod for Static Volatile Emissions of the South Coast Air QualityManagement District (California) which is incorporated herein byreference. This test is accepted as a predictor of volatile emissions inthe workplace during spray-up lamination procedures. Its results arereported in two ways--grams per square meter of weight loss, and thetime of emissions, in minutes and seconds. The latter measuremententails noting the point in time in which weight loss is no longerrecorded, thus requiring that weight be monitored beyond the time noted.

The test requirements are as follows: An environment at 77° C. and 50%relative humidity is maintained. If a controlled environment is notavailable, conditions should be reported for which measurements aremade. A 200 gm pre-promoted resin is weighed out into a suitable dry andclean container. The container is covered and placed in a 25° C.temperature bath. A balance is placed in a draft free enclosure. Agallon lid is cleaned with solvent and wiped dry. The diameter ismeasured to the nearest 0.1 cm. The gallon lid is placed on an invertedpaper or plastic cup mounted on the balance pan. A bent paper clip ispositioned in the center of the gallon lid. This weight (TARE WEIGHT) isrecorded. The container is taken from the temperature bath and anappropriate volumetric or weight measure of catalyst is added. A timeris started at this point. The catalyst is mixed with the resin for oneminute. The INITIAL WEIGHT is determined by pouring 100.0±0.5 gm ofcatalyzed resin into the can lid and recording the weight. Next, thepaper clip is used to determine when the resin has hardened sufficientlyto allow the resin or lid to be lifted. The time (gel time) is recordedat this point. The resin is then allowed to harden in the can lid andevery 15 minutes it is reweighed until concurrent weights agree towithin 0.05 gm. This is recorded as the FINAL WEIGHT. The entireprocedure should be repeated until duplicate samples agree to thenearest 5 gm/m².

The volatile emissions per square meter are calculated as follows:##EQU1##

The clear castings tests adopted were as follows:

1. Tensile strength--ASTM D638.

2. Tensile modulus--ASTM D638.

3. Elongation--ASTM D638.

4. Flexural strength--ASTM D790.

5. Flexural modulus--ASTM D790.

6. Heat deflection temperature--ASTM D648.

7. Water absorption at 150° F.--ASTM D570 (modified).

The water absorption test was modified as follows: the temperature wasset at 150° F. and long term immersion was set at one week. In the datareported in Table I, Resin A is as described above in terms of weight;it is, in molar equivalents, a polyester resin composed of 1.0 molemaleic anhydride, 2.0 moles phthalic anhydride, 0.42 mole diethyleneglycol and 2.71 moles propylene glycol. Sartomer CD480 is ethoxylatedbisphenol-A dimethacrylate where m and n in the above formula total 10.Sartomer 348 is ethoxylated bisphenol-A dimethacrylate where m and n inthe above formula are both 1. Mod L is 25% hydroquinone and 75%propylene glycol.

In Tables I and II, formulations containing both Sartomer and eitherstyrene or divinyl benzene are seen to compare very well in terms ofemissions with those not including styrene as a monomer.

From these it will be seen that the use of the alkoxylated BPAdimethacrylates have the effect of significantly reducing monomeremissions in styrene-containing laminating resins.

A volatility of 20.0 g/m² or less, as measured by the test of Section1162 of the Regulations of the South Coast (California) Air QualityDistrict, was significantly achieved by applicants in the presentinvention. In fact, applicants' resins all measured under 10.0 g/m².

                  TABLE I                                                         ______________________________________                                        RESIN        A2      C2      S     Z     Al                                   ______________________________________                                        Resin A      60.00   60.00   40.00 35.00 35.00                                Sartomer CD480                                                                             --      --      15.00 15.00 15.00                                Sartomer 348 --      --      20.00 20.00 20.00                                EG Dimethacrylate                                                                          --      --      25.00 10.00 20.00                                Vinyl Toluene                                                                              --      40.00   --    10.00 --                                   Cyclohexyl   --      --      --    10.00 --                                   Methacrylate                                                                  Divinyl Benzene                                                                            --      --      --    --    10.00                                Styrene      40.00   --      --    --    --                                   Mod L        0.20    0.22    0.06  0.12  0.12                                 RESIN                                                                         PROPERTIES                                                                    Gel time, min:sec                                                                          12:59   13:17   21:18 18:29 11:30                                interval, min:sec                                                                          5:58    6:54    4:32  4:11  3:26                                 Exotherm peak, °F.                                                                  345     324     249   276   294                                  Viscosity, cps, 75° F.                                                              315     340     1,390 426   624                                  1162 Emissions, G/M2                                                                       31.5    20.6E   3.6   6.1   9.7                                  Barcol hardness                                                               45 minutes   45      42      47    44    52                                   One hour     45      43      50    48    53                                   24 hours     49      49      52    51    54                                   CLEAR CASTING                                                                 PROPERTIES                                                                    Tensile strength, psi                                                                      9,308   7,555   8,069 9,635 8,176                                Ten. modulus, 10-5 psi                                                                     0.549   0.534   0.466 0.565 0.575                                Elongation, %                                                                              1.9     1.6     3.2   2.7   1.9                                  Flexural strength, psi                                                                     16,008  15,317  10,475                                                                              16,889                                                                              15,780                               Flex modulus, 10-5 psi                                                                     0.586   0.573   0.322 0.444 0.482                                Heat deflect. temp, °F.                                                             144     138     169   142   147                                  Water absorption,                                                             % at 150° F.                                                           One day      0.89    0.91    1.01  1.19  1.26                                 7 days       1.89    1.89    2.12  1.65  1.76                                 ______________________________________                                         E  This value was estimated based on the difference in results caused by      using different end points for the 1162 test.                                 A  The surfaces of the test specimens were alligatored. This indicates a      more severe problem than the weight gain indicates.                      

                                      TABLE II                                    __________________________________________________________________________    Low VOC Laminating Resins Based on General Purpose Polyester                  __________________________________________________________________________    Polymer                                                                       Resin         E-4  V-3  F-4  G-3 D-4 ZA                                       __________________________________________________________________________    Composition                                                                   Resin A       35.00                                                                              35.00                                                                              35.00                                                                              35.00                                                                             35.00                                                                             35.00                                    Sartomer 480  15.00                                                                              15.00                                                                              15.00                                                                              15.00                                                                             15.00                                                                             15.00                                    Sartomer 348  20.00                                                                              20.00                                                                              20.00                                                                              20.00                                                                             20.00                                                                             20.00                                    EG Dimethacrylate                                                                           --   --   --   --  10.00                                                                             10.00                                    Cyclahexyl Methacrylate                                                                     --   --   15.00                                                                              15.00                                                                             10.00                                                                             10.00                                    Styrene       30.00                                                                              --   15.00                                                                              --  10.00                                                                             --                                       Vinyl Toluene --   30.00                                                                              --   15.00                                                                             --  10.00                                    Mod L         00.10                                                                              00.20                                                                              00.05                                                                              00.17                                                                             00.00                                                                             00.06                                    12% Cobalt    00.30                                                                              00.30                                                                              00.30                                                                              00.30                                                                             00.30                                                                             00.30                                    16% Potassium 00.20                                                                              00.20                                                                              00.20                                                                              00.20                                                                             00.20                                                                             00.20                                    Dimethyl Acetoacetamide                                                                     00.30                                                                              00.30                                                                              00.30                                                                              00.30                                                                             00.30                                                                             00.30                                    Resin Properties                                                              Gel Time, min:sec                                                                           29:20                                                                              37:36                                                                              31:47                                                                              33:52                                                                             19:45                                                                             38:15                                    Interval, min:sec                                                                           10:35                                                                              09:49                                                                              11:25                                                                              07:07                                                                             10:15                                                                             07:37                                    Exotherm, °F.                                                                        301  273  220  244 231 277                                      Viscosity, cps @ 75° F.                                                              360  382  1570 560 990 710                                      Barcol                                                                        45 minutes    00.0 00.0 00.0 00.0                                                                              36.0                                                                              00.0                                     one hour      39.6 39.9 00.0 29.7                                                                              47.2                                                                              32.2                                     two hours     43.9 46.0 41.6 45.6                                                                              47.8                                                                              47.2                                     three hours   46.4 46.2 43.9 45.9                                                                              48.2                                                                              47.6                                     four hours    46.7 46.9 44.3 46.0                                                                              48.6                                                                              47.8                                     24 hours      46.9 46.9 43.9 47.2                                                                              48.5                                                                              48.7                                     1162 Emissions, G/M2                                                                        9.7  1.8  4.8  3.6 3.0 2.4                                      Emissions, min:sec                                                                          46:12                                                                              51:35                                                                              50:00                                                                              53:46                                                                             36:10                                                                             48:20                                    Properties of a Clear Casting                                                 HDT, °F.                                                                             147  138  127  138 133 138                                      Tensile strength, psi                                                                       7,610                                                                              9,500                                                                              8,930                                                                              9,580                                                                             7,950                                                                             10,370                                   Ten Modulus, 10-5 psi                                                                       0.442                                                                              0.501                                                                              0.452                                                                              0.485                                                                             0.454                                                                             0.540                                    Elongation, % 2.00 2.30 2.70 2.50                                                                              2.00                                                                              2.60                                     Flexural Strength, psi                                                                      >19,220                                                                            >19,150                                                                            >17,060                                                                            18,400                                                                            14,980                                                                            19,410                                   Flex Modulus, 10-5 psi                                                                      0.536                                                                              --   0.509                                                                              0.662                                                                             0.545                                                                             --                                       Water Absorption @ 150° F.                                             24 hours      1.07 0.81 1.30 1.07                                                                              1.22                                                                              1.04                                     seven days    1.81 1.43 2.16 1.78                                                                              2.09                                                                              1.87                                     __________________________________________________________________________    Resin         H-4  U-3  G-4  H-3 Controls                                     __________________________________________________________________________    Composition                                                                   Resin A       35.00                                                                              35.00                                                                              35.00                                                                              35.00                                                                             60.00                                                                             60.00                                    Sartomer 480  15.00                                                                              15.00                                                                              15.00                                                                              15.00                                                                             --  --                                       Sartomer 348  20.00                                                                              20.00                                                                              20.00                                                                              20.00                                                                             --  --                                       EG Dimethacrylate                                                                           15.00                                                                              15.00                                                                              15.00                                                                              15.00                                                                             --  --                                       Cyclohexyl methacrylate                                                                     05.00                                                                              05.00                                                                              --   --  --  --                                       Styrene       10.00                                                                              --   15.00                                                                              --  40.00                                                                             40.00                                    Vinyl Toluene --   10.00                                                                              --   15.00                                                                             --  --                                       Mod L         00.00                                                                              00.13                                                                              00.05                                                                              00.17                                                                             00.10                                                                             00.30                                    12% Cobalt    00.30                                                                              00.30                                                                              00.30                                                                              00.30                                                                             00.30                                                                             00.30                                    16% Potassium 00.20                                                                              00.20                                                                              00.20                                                                              00.20                                                                             00.20                                                                             00.20                                    Dimethyl Acetoacetamide                                                                     00.30                                                                              00.30                                                                              00.30                                                                              00.30                                                                             00.30                                                                             00.30                                    Resin Properties                                                              Gel Time, min:sec                                                                           09:22                                                                              38:05                                                                              15:26                                                                              25,10                                                                             05:00                                                                             23:22                                    Interval, min:sec                                                                           04:27                                                                              06:07                                                                              03:19                                                                              03:51                                                                             06:02                                                                             --                                       Exotherm, °F.                                                                        239  277  268  291 296 --                                       Viscosity cps @ 75° F.                                                               910  790  1100 650 440 440                                      Barcol                                                                        45 minutes    46.1 00.0 44.5 00.0                                                                              41.9                                                                              --                                       one hour      48.7 37.0 48.1 47.0                                                                              44.8                                                                              --                                       two hours     49.2 48.6 50.0 50.8                                                                              45.4                                                                              --                                       three hours   49.7 48.5 50.5 49.8                                                                              45.5                                                                              --                                       four hours    49.6 48.5 50.6 50.3                                                                              45.9                                                                              --                                       24 hours      50.4 48.5 50.3 50.7                                                                              46.2                                                                              --                                       1162 Emissions, G/M2                                                                        1.2  7.3  2.4  4.2 12.7                                                                              24.2                                     Emissions, min:sec                                                                          13:43                                                                              44:22                                                                              21:43                                                                              29:15                                                                             20:14                                                                             23:22                                    Properties of a Clear Casting                                                 HDT, °F.                                                                             143  136  147  159 144 --                                       Tensile Strength, psi                                                                       7,410                                                                              10,120                                                                             6,160                                                                              9,140                                                                             8,040                                                                             --                                       Ten Modulus, 10-5 psi                                                                       0.473                                                                              0.489                                                                              0.521                                                                              0.544                                                                             0.478                                                                             --                                       Elongation, % 1.80 2.70 1.50 2.00                                                                              1.80                                                                              --                                       Flexural Strength, psi                                                                      16,030                                                                             18,750                                                                             15,950                                                                             19,660                                                                            15,070                                                                            --                                       Flex Modulus, 10-5 psi                                                                      0.569                                                                              --   0.599                                                                              0.664                                                                             0.598                                                                             --                                       Water Absorption @ 150° F.                                             24 hours      1.23 1.06 1.17 0.95                                                                              1.01                                                                              1.01                                     seven days    2.14 1.78 2.14 1.84                                                                              2.11                                                                              2.11                                     __________________________________________________________________________

Accordingly, our invention is a method of laminating comprisingrepeatedly applying to a surface a composition comprising (a) the basepolyester polymer (resin) as described above and the alkoxylatedbisphenol-A diacrylate or dimethacrylate in a ratio of 2:1 to 0.5:1 and(b) about 10% to about 60%, based on the total of (a) and (b), of eitherstyrene, divinyl benzene or a combination thereof. In Tables I and II,the various "Sartomer" compositions, i.e. the ethoxylated bisphenol-Adimethacrylates, have 1 and 5 ethoxy groups on each side of thebisphenol-A; however, we may employ a single compound or compoundshaving any variation of combinations of ethoxy or propoxy groups fromtwo to about 20 groups, preferably a total of 2 to 10 alkoxy groups.

We claim:
 1. A laminating resin composition characterized by lowvolatile emissions comprising (A) a base unsaturated polyester resincomprising glycols, unsaturated polycarboxylic acids or derivativesthereof, and, optionally, saturated dicarboxylic acids and (B)alkoxylated bisphenol-A diacrylate or dimethacrylate having at least twoalkoxy groups, in a weight ratio of (A) to (B) of 2:1 to 0.5:1, and (C)about 10% to about 60% by weight, based on the total of components (A)and (B) of styrene and wherein said composition emits no more than 20.0g/m² of volatile emissions as measured by Section 1162 of theRegulations of the South Coast (California) Air Quality District. 2.Laminating resin composition of claim 1 including from 1% to about 10%,based on the overall composition, of N-vinyl pyrrolidone.
 3. Laminatingresin composition of claim 1 including from 1% to about 20%, based onthe overall composition, of cyclohexyl methacrylate.
 4. Laminating resincomposition of claim 1 including about 1% to about 30%, based on theoverall composition, of ethylene glycol dimethacrylate.
 5. Laminatingresin of claim 1 including about 1% to about 30%, based on the overallcomposition, of vinyl toluene.
 6. A laminating resin of claim 1 whereinthe weight ratio of (A) to (B) is about 1:1.